Quality of water in tanks of tadpole of bull frog, Rana catesbeiana Shaw, 1802, cultivated in different stock densities

The present work was carried out to evaluate the water quality in bullfrog tadpole tanks (Rana catesbeiana Shaw, 1802) under different stock densities. At the beginning of the experimental period, 680 tadpoles were used in G I phase, allotted to 16 plastic boxes of 34 liters capacity, as experimental units, divided into four sock densities (0.5, 1.0, 1.5, and 2.0 tadpoles/L) with four repplicates. The animals were fed four times a day with commercial powder diet, and the given amount was in function of the total biomass of each box, obtained from weekly biometrics. A daily partial renovation (20%) of the cultivation water was promoted, through the siphoning of diet orts and feces and weekly all the cultivation water was renewed, The water quality was weekly evaluated, through its physical and chemical variables (temperature, dissolved oxygen, pH, ammonia and electric conductivity). It was observed a reduction on the pH values, high ammonia and electric conductivity values, low dissolved oxygen values, mainly in the treatments with 1,5 and 2,0 tadpoles/liter. The stock density directly influenced the development of tadpoles and the water cultivation quality and, by the animal growth. The animals under lower population densities presented better productive performance.